1. Field of the Invention
This invention relates generally to vehicle lamps installed in vehicles such as automobiles having an air-hole structure for ventilating a lamp chamber and essentially consisting of a lamp body and a front lens. More particularly, this invention relates to a vehicle lamp so constructed as to improve waterproofness in such an air-hole structure.
2. Related Art
In vehicle lamps such as automobile lamps, a lamp body and a front lens are normally used to form a lamp chamber in which a reflector, a light source and the like are contained. If such a lamp chamber is airtight, moisture existing in the lamp chamber will not be allowed to escape therefrom. When the outside air temperature lowers, the moisture condenses on the front lens and results in the deterioration of the light-distribution characteristics of the lamp, or the degradation of the external appearance of the lamp. For the reason stated above, an air hole for communicating the inside of the lamp chamber with the outside air has, heretofore, been provided in several places of the lamp body. However, simply making the air hole allows rain or muddy water to penetrate into the lamp chamber through the air hole, thus impairing the function of the lamp. Consequently, it has been proposed to provide an air-hole structure using a cover for covering the air hole in order to secure ventilation and to prevent water from penetrating from the outside.
FIGS. 6(a) and 6(b) are perspective views of an example of such an air-hole structure; and FIG. 7 is a vertical sectional view thereof. A cylindrical air hole 201 for communicating the inside of a lamp chamber with the outside thereof is made in a plurality of places vertically in the back of a lamp body 11. An outer cylindrical wall 202 having a cutout is provided on the circumferential lower side of the outer periphery of each air hole 201, and rectangular waterproof walls 203-206 are uprightly provided on the respective four peripheral positions of the air hole 201. A rectangular, plate-like waterproof cover 207 capable of bending (i.e., elastic) deformation is integrally coupled to the waterproof wall 203 positioned on the upper side of the lamp.
In this example, the waterproof cover 207 is capable of bending deformation at its coupling portion 208. As shown in FIG. 6(b), a projection 211 formed at the leading end of the waterproof cover 207 mates with a retaining hole 210 provided in the lower-side waterproof wall 206 when the waterproof cover 207 is subjected to the bending deformation so as to be substantially perpendicular to the lower-side waterproof wall 206 so that the area surrounded by the waterproof walls 203-206 can be covered with the waterproof cover 207, and so that the air hole 201 can be covered with the waterproof cover 207 and the waterproof walls 203-206.
The outside water which is likely to penetrate into the lamp chamber through the air hole 201 can thus be blocked by covering the air hole 201 with the waterproof cover 207 and the waterproof walls 203-206 and further with the outer cylindrical wall 202 and the cylindrical wall of the air hole 201. On the other hand, ventilation in the lamp chamber from the outside is secured through the gaps between the respective waterproof walls 203-206, the gaps between the respective waterproof walls 204 and 205, and the cutout of the outer cylindrical wall 202. Normally, arrangements for increasing the air permeability of the lamp chamber are often adopted by providing an air-hole structure of this sort in the upper and lower portions of the lamp body and circulating air within the lamp chamber through the upper and lower air holes.
Although ventilation is secured through the gaps between the waterproof cover 207 and the respective waterproof walls 203-206 in the conventional air-hole structure, the outside water is conversely allowed to penetrate into the waterproof walls 203-206 through the gaps and may penetrate into the lamp chamber through the air hole 201 unless the dimensions of the gaps are precisely controlled because the gaps formed with the waterproof cover 207 and the respective edge portions of the waterproof walls 203-206 are extremely finely dimensioned. As the probability is high that the air-hole structure located on the upper side of the lamp body of the automobile in particular is exposed to rain and muddy water, moisture is allowed to readily penetrate into the lamp body. Since the waterproof cover is in the form of a flat plate, it is likely to undergo plastic deformation and causes the gap between the waterproof cover and the waterproof wall to be enlarged and this may reduce the waterproofing effect further.
The waterproof walls 203-206 and the waterproof cover 207 constituting the air-hole structure are resin-molded integrally with the lamp body. In the molding of the air-hole structure of the example above, molds K11 and K12 are provided with sliders S11 and S12, each escaping toward the upper and lower sides of the lamp and crossing the parting direction of the molds used for resin-molding the lamp body 11 as shown by arrows in FIG. 7. The slider S11 is used to form a concave groove 209 in a coupling portion 208 between the waterproof cover 207 and the lamp body 11. The slider S12 is used to form a retaining hole for retaining a projection provided at the leading end of the waterproof cover. Consequently, the resin molding procedure for the air-hole structure requires a space on both the upper and lower sides of the lamp. However, when the air-hole structure is required to be arranged right above or below a bulb-socket inserting hole formed in the back of the lamp body, for example, one of the sliders S11 and S12 will interfere with the sleeve of the bulb-socket inserting hole, thus restricting the movement of that slider. Therefore, the aforementioned air-hole structure becomes difficult to arrange.